1. Field of the Invention
The present invention relates to optical devices which perform optical modulation, optical detection or optical logic operation, and more particularly to optical quantum interference devices which are suitable for use in optical integrated circuits such as optical computers or OEICs and have high response speed, and methods of manufacturing these devices.
In the present specification, the term "light" is used to denote electromagnetic waves generally.
2. Description of the Related Art
Using computers which perform logic operations by turning on and off a small current and by storing and emitting small charges, together with software has, greatly advanced the quest for an increase in the operation speed and miniaturization thereof. Recent interesting researches are to handle currents and fields by quantum-mechanical descriptions from the standpoint of interaction of electrons and a microfield such as that represented by a quantum well. For example, a phenomenon in which the electric conductivity of a semiconductor fine loop exhibits a magnetic vibration due to Aharanov-Bohm effect known as one of quantum interference effects, is described in PHYSICAL REVIEW LETTERS, Vol. 55, (1985), pp. 2344-2347. The Aharanov-Bohm effect is explained by a pure quantum-mechanical description that the wavefunction of electrons is affected by the vector potential of a magnetic field even if the electrons do not directly pass through a localized magnetic field to thereby change the phase of the wavefunction. This effect can be observed in the form of interference of electrons affected by the vector potential.
A light absorption modulation of excitons in a quantum well due to optical Stark effect is described in PHYSICAL REVIEW LETTERS, Vol. 56, (1986), pp. 2748-2751. The optical Stark effect is a non-linear optical effect and a phenomenon in which the energy level of excitons is shifted by interaction with an optical field.
A two-photon optical process due to the interaction of excitonic polaritons is described in SOLID STATE COMMUNICATIONS, Vol. 33, (1980), pp. 1135-1138.
The above conventional techniques use an electron quantum interference phenomenon due to the Aharanov-Bohm effect to modulate the conductivity of a semiconductor by sweeping the intensity of a magnetic field applied externally.
The absorption intensity modulation using the optical Stark effect of quantum well excitons and the interaction between the excitonic polaritons is difficult to realize intensity modulation at a practical efficiency.